Porous diatomite-mixed 1,4,5,8-NTCDA nanowires as high-performance electrode materials for lithium-ion batteries

Conjugated Phthalocyanine-Based Mesoporous Covalent Organic Frameworks for Efficient Anodic Lithium Storage

Organic anode materials have been recognized as promising candidates for low-cost and sustainable lithium-ion batteries (LIBs), which however suffer from the inferior cycling stability and low conductivity with unsatisfactory LIBs performance. Herein, two conjugated phthalocyanine-based covalent organic frameworks (COFs), namely CoPc-Ph-COF and CoPc-3Ph-COF, are synthesized by the nucleophilic substitution reaction of hexafluorophthalocyanine cobalt (II) (CoPcF16) with 1,2,4,5-tetrahydroxybenzene and 9,10-dimethyl-2,3,6,7-tetrahydroxyanthracene, respectively. Powder X-ray diffraction and electron microscopy analysis reveal the crystalline porous structure of both COFs with a pore size of 1.6-2.4 nm, enabling facile ion transportation. Immersion experiments demonstrate the excellent stability of both COFs. I-V curve measurement discloses the superb conductivity of both COFs due to their fully π-conjugated frameworks. These merits, in combination with their N-rich skeleton, endow the two COFs with excellent anodic Li+ storage performance in terms of high specific capacities, superb rate performance, and good cycling stability. In particular, CoPc-3Ph-COF suggests a large reversible capacity of 1086 mA h g-1 at 100 mA g-1, superior to most reported organic LIBs anodes, exhibiting its promising application in high-performance LIBs.

Two Birds One Stone: Graphene Assisted Reaction Kinetics and Ionic Conductivity in Phthalocyanine-Based Covalent Organic Framework Anodes for Lithium-ion Batteries

This work reports a covalent organic framework composite structure (PMDA-NiPc-G), incorporating multiple-active carbonyls and graphene on the basis of the combination of phthalocyanine (NiPc(NH2 )4 ) containing a large π-conjugated system and pyromellitic dianhydride (PMDA) as the anode of lithium-ion batteries. Meanwhile, graphene is used as a dispersion medium to reduce the accumulation of bulk covalent organic frameworks (COFs) to obtain COFs with small-volume and few-layers, shortening the ion migration path and improving the diffusion rate of lithium ions in the two dimensional (2D) grid layered structure. PMDA-NiPc-G showed a lithium-ion diffusion coefficient (DLi + ) of 3.04 × 10-10 cm2 s-1 which is 3.6 times to that of its bulk form (0.84 × 10-10 cm2 s-1 ). Remarkably, this enables a large reversible capacity of 1290 mAh g-1 can be achieved after 300 cycles and almost no capacity fading in the next 300 cycles at 100 mA g-1 . At a high areal capacity loading of ≈3 mAh cm-2 , full batteries assembled with LiNi0.8 Co0.1 Mn0.1 O2 (NCM-811) and LiFePO4 (LFP) cathodes showed 60.2% and 74.7% capacity retention at 1 C for 200 cycles. Astonishingly, the PMDA-NiPc-G/NCM-811 full battery exhibits ≈100% capacity retention after cycling at 0.2 C. Aided by the analysis of kinetic behavior of lithium storage and theoretical calculations, the capacity-enhancing mechanism and lithium storage mechanism of covalent organic frameworks are revealed. This work may lead to more research on designable, multifunctional COFs for electrochemical energy storage.

Phenediamine bridging phthalocyanine-based covalent organic framework polymers used as anode materials for lithium-ion batteries

In this study, phenediamine bridging phthalocyanine-based covalent organic framework materials (CoTAPc-PDA, CoTAPc-BDA and CoTAPc-TDA) with increasingly-widening pore sizes are prepared by reacting cobalt octacarboxylate phthalocyanine with p-phenylenediamine (PDA), benzidine (BDA) and 4,4''-diamino-p-terphenyl (TDA), respectively. The effects of frame size on the morphology structure and its electrochemical properties were explored. X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and transmission electron microscopy (TEM) images show that the pore sizes of the CoTAPc-PDA, CoTAPc-BDA and CoTAPc-TDA are about 1.7 nm, 2.0 nm and 2.3 nm, respectively, which are close to the simulated results after geometric conformation optimization using Material Studio software. In addition, the specific surface areas of CoTAPc-PDA, CoTAPc-BDA and CoTAPc-TDA are 62, 81 and 137 m² g^-1, respectively. With increase in the frame size, the specific surface area of the corresponding material increases, which is bound to produce different electrochemical behaviors. Consequently, the initial capacities of the CoTAPc-PDA, CoTAPc-BDA and CoTAPc-TDA electrodes in lithium-ion batteries (LIBs) are 204, 251 and 382 mA h g^-1, respectively. As the charge and discharge processes continue, the active points in the electrode material are continuously activated, leading to a continuous increase in charge and discharge capacities. After 300 cycles, the CoTAPc-PDA, CoTAPc-BDA and CoTAPc-TDA electrodes exhibit capacities of 519, 680 and 826 mA h g^-1, respectively, and after 600 cycles, the capacities are maintained at 602, 701 and 865 mA h g^-1, respectively, with a stable capacity retention rate at a current density of 100 mA g^-1. The results show that the large-size frame structure materials have a larger specific surface area and more favorable lithium ion transmission channels, which produce greater active point utilization and smaller charge transmission impedance, thus showing larger charge and discharge capacity and superior rate capability. This study fully confirms that frame size is a key factor affecting the properties of organic frame electrodes, providing design ideas for the development of high-performance organic frame electrode materials.

Graphene in situ composite metal phthalocyanines (TN-MPc@GN, M = Fe, Co, Ni) with improved performance as anode materials for lithium ion batteries

In view of the disadvantage of the limited active site utilization due to the easy aggregation of phthalocyanine compounds, three kinds of graphene composite metal phthalocyanines (TN-MPc@GN, M = Fe, Co, Ni) were prepared using an in situ composite method, and their electrochemical properties were investigated as anode materials for lithium-ion batteries.

A phthalocyanine-grafted MA-VA framework polymer as a high performance anode material for lithium/sodium-ion batteries

A porous MA-VA-PcNi polymer was prepared by grafting nickel phthalocyanine (PcNi) onto the main chain of a maleic anhydride-vinyl acetate (MA-VA) polymer, and an MA-VA-PcNi electrode is prepared by electrospinning technology to inhibit the agglomeration of the active powder effectively, which produces spherical particles with a diameter of 100-300 nm. The synthesized MA-VA-PcNi polymer is used as the anode for lithium-ion and sodium-ion batteries, exhibiting excellent energy storage behaviors. The MA-VA-PcNi/Li battery displays a high capacity of 610 mA h g-1 and can still remain at 507 mA h g-1 with a retention rate of 83.1% after 400 cycles at a current density of 200 mA g-1. Even at a high current density of 2 A g-1, the specific capacity can remain at 195 mA h g-1. In addition, the MA-VA-PcNi/Na battery displays a high capacity of 336 mA h g-1 and can still remain at 278 mA h g-1 with a retention rate of 82.7% after 400 cycles at a current density of 100 mA g-1. A high specific capacity of 164 mA h g-1 can also be achieved at a high current density of 1 A g-1. After nickel phthalocyanine (PcNi) was grafted onto the MA-VA polymer, aggregation between phthalocyanine rings was effectively prevented, and this exposes more active sites. At the same time, the spherical particles obtained by electrospinning technology further improve the dispersion and increase the number of active sites of the active materials. Finally, the electrode materials show excellent energy storage behavior for lithium-ion and sodium-ion batteries, which provides a new idea for designing high-performance energy storage materials for organic electrodes.

Fabrication of conjugated polyimides with porous crosslinked networks and their application as cathodes for lithium-ion batteries

We synthesized a series of conjugated porous polymers with crosslinked networks and assessed their performance as cathodes for lithium-ion batteries.

Graphite-like structure of disordered polynaphthalene hard carbon anode derived from the carbonization of perylene-3,4,9,10-tetracarboxylic dianhydride for fast-charging lithium-ion batteries

The graphite-like PTCDA-1100 hard carbon is prepared, which exhibits mixed porous structure with wider layer spacing, larger specific surface area and more exposed active points. As a result, superior rate cycle behaviors for both PTCDA-1100/Li half-batteries and PTCDA-1100/NCM-811 full batteries are observed.

Facile preparation of MoS2/maleic acid composite as high-performance anode for lithium ion batteries

We propose a facile one-step method to prepare a MoS₂ composite anode with excellent electrochemical performance and potential for practical applications in lithium ion batteries.